Wars Fought in a Computer
by reminiscent-afterthought
Summary: [AU] Rei is only interested in Kaiba's virtual world insofar as it getting him Hajime back. Noah is interested in Hajime a little bit more, because it's inaction and inability that's caused the mess (again) - except where does the mysterious "L" fit in?


**A/N:** Written for

The Presents Under the Tree! DFC 2017 Christmas Event! - for Higuchimon  
Becoming the Tamer King Challenge, Silver Task 3 - Write a baby-sitting job (or not technical jobs if you prefer) in which the baby-sitee gives the baby-sitter the slip  
Diversity Writing Challenge, h49 - write a crossover with one fandom AU and the other in canon

* * *

 **Wars Fought in a Computer**  
Chapter 1

.

Rei's initial interest in the matter is purely curiosity, with maybe a dash of pride. A challenge goes out on one of the hacker forums he frequents and there's no monetary reward so not necessarily worth his time. Still, he'll get to meet one of the world's top hackers if he finds him first and that can teach him something (or nothing, because he's not great at learning from people), but it'll speak volume of his skills thereafter.

Sadly, it doesn't work that way. He solves the puzzle, yes, and as far as he can tell he's solved it first. But his little brother tags along with him to KaibaLand and therein lies his mistake.

Hajime vanishes into the virtual world and Rei is left with a new puzzle to solve.

And Kaiba Seto might not have been the person to pose the initial challenge (because all one had to do was walk into his office at KaibaCorp to find him) but he was a formidable programmer, strategist and businessman. Not to mention Kaiba Seto won't hesitate to bury anyone who rubbed him the wrong way.

But Katsura Rei won't hesitate to do whatever it takes to get his brother back, so he has that going for him, at least.

.

Noah has been quite lonely, since the visitors left. Sure, his father is around somewhere, and the Big Five, but he's never gotten along with any of them and after the whole incident with Yugi and Seto, it's in his best interests to avoid them.

He'd tried to give them the slip but apparently his programming skills weren't quite up to par. Still, they aren't bothering him at the moment.

That probably means they're plotting something but it's not worth poking around and lighting incidental fires to find out quite yet. If something does happen… well, he'll deal with it then. It might be nothing. His father's not the brightest tool in the toolbox anymore. Kaiba Seto had out-foxed him more than once, after all.

He's been busy creating his new home, after all. It's reminiscent of the old one, for the most part. Better the devil you know as the saying goes and he's not exactly known for his creativity. It doesn't run in the family, adopted or otherwise, either since they're always hiring. Or leaving the design aspects of things to Industrial Illusions.

Really, those two companies can stand to get along a lot better than they do.

But as much as he tries to dismiss the proverbial couldren stirring in his new world, he can't help but feel worried.

And as much as he is relieved that Seto and Mokuba and Yugi and all the others made it out alright, he can't help but feel rather lonely too.

And then, suddenly, he has company. And an idea of what his father and old associates have been up to all this time.

.

Hacking into KaibaCorp is damn near impossible, though not for lack of trying. Sadly, most of Rei's attempts leave him covering his tail almost immediately, and he simply can't keep that ridiculously tight security off his tail and actually look for what he needs to at the same time.

But he's not going to trust other anonymous hackers who are probably still trying to find this "L" to rescue his brother. Especially since "L" hasn't declared an end to their little game and the rest of the hacker world still thinks the gauntlet's thrown.

At least no-one's launched a public attack on KaibaCorp since the whole Schroeder mess during the KC Grand Championship… but at this point he wonders if it'd be a blessing in disguise. Distract them, so to speak, so they wouldn't realise a solo hacker's sneaking in through the back door.

No such luck though. He'll have to do it without help, incidental or otherwise.

It's too bad his empty milk and juice packets can't type on keyboards, he thinks – and then he scolds himself. That's childish, and he doesn't have the time to waste on such childishness.

And when there's suddenly a message on his computer – _I can help you – no,_ he thinks. Nobody can help.

.

Noah's company is, unfortunately, on the sleepy side. Rather, he's been asleep since he arrived in a cute little pillow-shaped avatar and he's been sleeping since.

Noah's curious by nature though (if only because he's got nothing better to do) and so he researches. And it takes longer than it should to find who he might be because apparently not everybody's heard of a Missing Person's report.

Though it helps that both sibliings stay at home and the elder one's dodging the line of the law with his hacking. But everything leaves a trail, and so Noah is able to lock in on him.

He sends a message, because that Katsura Rei is definitely frantically searching for his little brother.

Katsura Rei, unfortunately, isn't the kind who takes help from random messages on the computer.

 _Okay,_ Noah thinks. He's worked with Kaiba Seto (and against him, but that's a moot point, now). He can get Katsura Rei to see he's not a fluke or, worse, an enemy. That would be simpler of Hajime looked like Hajime instead of a pillow, but he can still do something.

The straight-forward thing is to change him back into human form, but it's not a simple job in the least and he wants to move faster than that. Seto loses his head whenever Mokuba goes missing, and Kastura Rei is pretty similar. He wonders, then, if that means Hajime's personality is similar to Mokuba (or maybe his own, instead), but that's something he can hopefully discover at his leisure (unless someone blocks him once all is said and done, but he's on the good side this time!).

He can work on turning Hajime the pillow-avatar back into Hajime the human (assuming it's not beyond his ability, of course), but it's probably more productive to nip the problem in the bud first. Which means kicking Kaiba Gozaburo and the Big Five out of his garden once and for all… and preferably put them into a virtual Fuchu Prison so they can't cause trouble anymore. He can't manage it himself. And he has enough pride not to ask Seto unless it's a life or death situation.

And it isn't. Yet. He can manage this much, if he teams up with Katsura Rei.

But apparently Katsura Rei needs a bone thrown at him to get him to agree.

And it's not like revealing his name will be a problem.

.

Another message comes. _I know where your brother is._

That one's more telling… and more suspicious, because he hasn't reported Hajime's disappearance to anyone and, as far as he knows, only he himself and the mysterious "L" should know what's happened.

 _Are you L?_ he replies. It's probably a lost cause, but in the interim he can try and track the IP address.

Which is apparently a server in KaibaCorp, so he can't get very far before security's on his trail again.

But he's not going to waste his time learning a children's card game than is useful for anything except KaibaCorp security.

 _L?_ comes the reply. _No, my name's Kaiba Noah. You can verify it with my brothers if you like (though I recommend Mobuka; he's easier to talk to._

Rei stares at that message, because of course he knows the name Kaiba… but a Noah? He hasn't heard about that at all. As for the verification… there's an email address as well, and Rei taps out a quick query because he can more than handle covering his tracks in that.

And the reply comes, the next day. A summary that's glossing over certain parts of the tale but surmises that, yes, Noah is a stepbrother of the two currently at the head of KaibaCorp, and is immortalised in Kaiba's virtual world after a car accident robbed him of his life in the real world.

 _Nice story,_ he replies. He doesn't have sympathy to spare. _But that doesn't tell me anything._

The reply comes back instantly. _Long story short: my dear old father – the guy who used to run KaibaCorp as a military facility – tried to kill my stepbrothers, but they put a plug in that plan. Unfortunately, he and his henchmen hijacked my new virtual world and kidnapping your brother and turning him into a green pillow apparently has something to do with their new plan._

 _And as much as I'd like pleasant company, a green pillow isn't really conversational and I'm not about to keep brothers apart, so I'll help you. And you can help me get rid of the bad guys._

Rei frowns. The guy's presuming he'll help, but he works alone and he's got no reason to trust a virtual guy. And no reason to play cleaner, either.

But can he afford to let his only hint go?

 _Prove it,_ he sends finally.

And he goes back to trying to hack the KaibaCorp satellite in the radio silence that, predictably, follows.


End file.
